Not on the list

Not an emergency

On February 2, 2007, a Beechcraft King Air 200 departed from Rogers, Arkansas, on a positioning flight to Virginia’s Shenandoah Valley Airport. The flight was under the command of a company pilot, a multiengine airline transport pilot. About 110 of his 4,050 total hours were in B200 airplanes. His co-pilot was a friend, not employed by the operator, whom the pilot in command (PIC) had invited along to build make-and-model time. He held a multiengine instructor certificate and had accumulated 28 hours in type, but without completing any formal transition training.

About half an hour after takeoff, in cruise flight at FL270 with the co-pilot on the controls, the inner pane of the two-ply left windshield shattered. The cockpit voice recorder picked up “a very loud snap” followed by the PIC asking, “What’d you break?” Fifteen seconds after the snapping sound, the PIC announced, “Gonna dump the cabin.” He later explained that he wasn’t confident of the windshield’s integrity.

As it happens, this wasn’t an issue. The B200’s checklist for a windshield fracture calls for descending to FL250 or below “if possible” and maintaining cabin differential pressure of 2.0 to 4.6 psi. Further, the Limitations section of the POH gives the operator discretion to continue using the airplane for up to 25 hours with a cracked or shattered windshield.

Compound errors

Twenty-six seconds after dumping cabin pressure, the co-pilot observed, “We need to go on oxygen.” That was the last statement recorded from him; the sound of his breathing suggested that within another 30 seconds he’d lost consciousness. The pilot tried to activate the system using first the left handle, which he found “hard to pull,” and then the right, which deployed the masks in the passenger cabin. The cockpit voice recorder (CVR) recorded three comments suggesting that he wasn’t receiving oxygen, either, before he also passed out—a minute and a half after depressurizing the cabin. His last recollection was of disconnecting the autopilot and pitching forward to initiate an emergency descent. He didn’t remain conscious long enough to reduce power or lower the landing gear.

The pilot subsequently acknowledged that, contrary to Beechcraft’s “Before Engine Start” checklist, he’d turned the oxygen tank shutoff valve to Off before takeoff to “save the supply.” Whether because of hypoxia or alarm over the anomaly, neither pilot remembered to turn it back on.

Radar data showed the King Air descending almost 18,000 feet in just over five minutes. The CVR recorded only the gear and overspeed warning horns, a series of altitude alerts, and increasing wind noise until it abruptly disconnected seven minutes after the pilot’s last comment—apparently when its 4-G impact switch was triggered.

A miraculous escape

The 4-G loading was not due to impact, but the crew’s efforts to recover control of the aircraft after regaining consciousness. After leveling off at about 7,000 feet, the pilot declared an emergency with Memphis Center and was given vectors to Cape Girardeau, Missouri, where their landing was “uneventful.”

In his written report to the NTSB, the pilot commented that after the recovery the airplane was “difficult to control.” Little wonder! The post-accident inspection found both wings wrinkled. The outboard two-thirds of the left horizontal stabilizer and elevator were gone, along with the outer third of the right elevator; what remained was held on only by the inboard hinge. The fact that it could be controlled at all reaffirmed the King Air’s reputation as a stout airframe. (And when tested, the oxygen system worked normally.)

Checklist, checklist

Investigators found a one-page checklist of unknown origin in the cockpit, which the pilot said “came with the airplane” and he acknowledged using it instead of those provided in the POH. It did not include the procedure for a cracked windshield, and neither the Before Start or After Start sections specified activating the oxygen system (although the pilot admitted knowing it was called for by the factory checklist). While it may have been incomplete, whoever compiled it had a sense of humor. The last item under “Shut Down” was “Pajamas...As Req.”

Potentially adding to the pilot’s confusion was the fact that while the checklist for a cracked windshield does not call for dumping cabin pressure, the checklist for a cracked side window does. The dissimilarity of procedures for dealing with ostensibly similar anomalies is another argument for limiting memory items to those emergencies that require immediate response—another list that has to be memorized.

David Jack Kenny is an aviation writer specializing in accident analysis and safety topics, and a former statistician for AOPA’s Air Safety Institute.